Earthdata Forum

Hi ASF/HyP3 team,

I currently use HyP3 for Sentinel-1 InSAR processing. However, Sentinel-1 is C-band and coherence often degrades over vegetated/mountainous areas. In my region (many mountainous/forested slopes), C-band InSAR frequently fails to maintain coherence, so I’m very interested in NISAR (L-band) for routine monitoring and evaluation.

Will NISAR data (e.g., GSLC / GUNW / RTC) be supported in ASF HyP3 in the future? If so, is there any public roadmap or tentative timeline for when HyP3 processing will become available for NISAR?

If others are also interested, please reply with your use case (e.g., landslides/infrastructure/agriculture), desired product types, and urgency—so community demand is visible.

Thank you.

Regards
Yoshi Iwasa
Ehime pref,Japan

Yoshi,

Thank you for highlighting your use case. Forested, mountainous terrain is exactly where L-band shines, and your feedback helps us prioritize our efforts.

We are currently working with NASA ESDIS and JPL to find a cost-effective way to process NISAR’s massive data volume. Our goal is to provide interoperable, analysis-ready products while staying within our budgetary limits.

• Will HyP3 support NISAR? We are actively evaluating this. It is a high-priority option, but the final decision depends on available resources.
• Where is the roadmap? We will be adding a development roadmap to the NISAR Data User Guide around the time of the next data release (expected next month).

Please keep sharing your specific needs for L-band products; it provides the "community demand" data we need to justify these tools to NASA!

-- Kirk, ASF NISAR Project Manager

@iwa103,
The NISAR mission makes some higher-level products available directly in the archive without the need for additional processing. This includes Geocoded SLCs (GSLC), 12-day Geocoded Unwrapped Interferograms (GUNW), and Geocoded Covariance (GCOV) products, which can be used in place of an RTC product (they contain radiometrically terrain corrected values in gamma-0 power for each available polarization). ASF makes all of these mission products available for download or direct S3 access. Refer to the Data Products section of the NISAR Data User Guide for more information about the product types generated as part of the mission.

There are already some sample products available in the archive, with more scheduled to arrive starting today, allowing you to take a look at these products to determine if they are suitable for your analysis workflows. Keep in mind that the currently available NISAR products are not fully calibrated, and contain artifacts. We expect calibrated products to be delivered to the archive starting this summer.

As @khogenso mentioned, there may still be use cases for on-demand processing when the archived products don't meet your needs. While we are not yet able to commit to specific on-demand processing support, it would be helpful to know what functionality is most important to our users as we evaluate available options. For example, are you looking for the ability to customize the level 2 products already available (custom GUNW date pairs, different processing parameters, different output pixel spacing or file format, etc.), or are you requesting that level 3 algorithms be implemented that take GUNW/GSLC/GCOV as input?

Thanks for your interest in NISAR!

I checked GUNW product and my comment is below.

1.spatial resolution
In the GUNW products, the pixel spacing appears to be approximately 20 m for the wrapped interferogram and about 80 m for the unwrapped phase and coherence layers. In contrast, HyP3 allowed users to select between higher and lower spatial resolutions. At present, the inability to choose the spatial resolution in GUNW is a somewhat limiting aspect from the user perspective.

2. SBAS compatibility
I understand that GUNW products are primarily generated for 12-day interferometric pairs. However, typical SBAS analyses require multiple temporal baselines, such as 24-day and 36-day pairs, in order to construct a stable interferometric network.

If possible, the availability of GUNW pairs up to three cycles (e.g., 24- and 36-day intervals) would make it significantly easier to conduct SBAS analysis using tools such as MintPy. Given the expected improvement in coherence over vegetated areas with L-band data, expanding compatibility with SBAS workflows would be particularly valuable.

3.Comparison with HyP3
On the other hand, HyP3 had monthly credit limits that restricted the number of processing runs. In contrast, the absence of such usage limitations for GUNW products can be considered a major advantage.

If possble NISAR RSCL can run by HyP3, it could be helpful, but not nessecary.

Yoshi Iwasa
Japan, Ehime Pref

Thank you for your input, Yoshi. I know that many involved with the NISAR project are watching the Forum for feedback and questions, and will take note of your observations and perhaps respond.

Here is additional comment.

The availability of analysis-ready data in the GUNW product is very helpful.

In most cases, analysis using the standard 12-day interval data should be sufficient. However, when weather conditions are unfavorable, it may be necessary to analyze pairs that span an additional cycle (e.g., 24 days). Since this would not be required for every case, it would be useful if HyP3 allowed users to process arbitrary pairs.

If that were possible, it could also help address the need to generate SBAS pairs with longer temporal baselines (e.g., 24 or 36 days).

Thank you, Yoshi.

hecked the LiCSAR public products as a reference to understand how NISAR GUNW products might be used for time-series analysis.

In LiCSAR, InSAR results are not provided only as consecutive interferogram pairs. Instead, multiple interferograms are generated for each observation (master) using several later observations (secondary). For example, in the frame 090D_05651_051011, the structure looks like the following.

Master Secondary1 Secondary2 Secondary3 Secondary4
2024-12-17 2024-12-29 2025-01-10 2025-01-22 2025-02-03
2024-12-05 2024-12-17 2024-12-29 2025-01-10 2025-01-22
2024-11-23 2024-12-05 2024-12-17 2024-12-29 2025-01-10

In this way, multiple interferograms are produced for a single master acquisition, forming an interferogram network. In the frame I checked, there were about 883 interferograms in total.

Because such an interferogram network is available, users can easily perform time-series analysis such as SBAS.

Therefore, if NISAR GUNW products are provided in a similar way, including interferograms with multiple temporal baselines rather than only consecutive pairs, they could likely be used directly for SBAS time-series analysis.

I would like to ask whether NISAR GUNW products are planned to be distributed in a way similar to LiCSAR (i.e., providing an interferogram network), or whether users are expected to generate additional interferogram pairs themselves.

The NISAR mission will be generating only the nearest-neighbor GUNW products (12-day interferograms). These products will be processed automatically as new data is acquired, and archived for public use. Custom pairings for other date ranges would currently need to be generated by users themselves.

Ideally, we would like to provide On Demand processing for custom GUNW pairings, but that is subject to resource availability, as @khogenso mentioned. Thank you for providing your feedback, @iwa103; it helps inform our evaluation of potential service development.

Thank you for your explanation.

It is not strictly necessary for all interferograms to be provided as GUNW products. If providing custom GUNW pairings on demand is difficult due to resource limitations, it would be very helpful if NISAR data could at least be supported in the existing HyP3 service.

In that case, even the 12-day pairs could be processed through HyP3. However, for SBAS analysis, it is important that the processing parameters remain consistent across interferograms. Therefore, support through the current HyP3 framework would be highly desirable.

This is particularly important for L-band SAR. In countries with dense vegetation, such as Japan, L-band is much more effective for InSAR analysis. Japan has L-band data from ALOS, but it is not freely available, which makes it difficult to perform SBAS analyses in practice.

The same issue exists in many parts of Southeast Asia, where vegetation is also dense. Ideally, L-band should be used instead of C-band for these regions. However, because Japanese L-band data are expensive, many researchers are currently forced to conduct SBAS analyses using C-band data instead.

For this reason, the availability of open L-band SAR data is extremely important from a global perspective. I hope that support for processing services such as HyP3 will be positively considered.

Thank you for your efforts and for considering this feedback.